1. Field of the Invention
The present invention relates to electrophotographic imaging apparatus, and more particularly to a waste toner collection apparatus used therein.
2. Description of the Related Art
In the electrophotographic process commonly used in imaging apparatus such as laser printers, copy machines and the like, an electrostatic image is created upon a photosensitive member, such as a roll or belt. Visible electroscopic marking particles, commonly referred to as toner, are applied to the electrostatic image on the photosensitive material. Thereafter, the toner image is transferred to the desired media, which may include paper, transparency sheets or the like. The toner image is subsequently affixed to the underlying media by the application of heat and pressure in a fuser.
While a substantial portion of the toner image is transferred to the media, a residual amount of toner may remain on the photosensitive member. To prepare the photosensitive member for receiving a subsequent electrostatic image, and an accurate toner image thereof to transfer to a subsequent media, it is necessary to clean the photosensitive material, and remove all residual toner from the previous image. Toner remaining from the previous image can decrease the print quality of a subsequent image. A known method for removing residual toner includes the operation of a scraping blade of elastomeric material against the photosensitive material. The residual toner is scraped from the photosensitive material and collected in various ways for subsequent transfer to a waste toner tank or container. Periodically, the waste toner container can be emptied, or simply removed and replaced with an empty container. However, such a removal process can be messy, and contamination of the machine interior can adversely affect print quality. Clean-up thereof is difficult.
It is desirable that waste toner collection capacity be sufficient to correspond with machine page life expectancy, so that removal of the waste toner container from the machine can be performed by trained personnel as part of life-expectancy servicing. A smaller capacity container requires design for periodic user servicing, or can result in service calls simply to remove and empty or replace the waste toner container.
Even with the high toner transfer efficiencies common in present day machines, with the extended life expectancy also common in current machines, the interior machine space required for waste toner collection can be significant. For example, assuming a 90% transfer efficiency of toner to media in a machine having a 100,000 page life expectancy, it may be required to collect as much as 760 grams or 1,810 cc of toner (assuming 0.42 g/cc). Assuming 100% packing efficiency of the space inside the container, a container having a 1,810 cubic centimeter volume is required. If the waste toner container is not efficiently packed with waste toner, a larger volume is required, which may present design difficulties in current machine compact architecture having limited internal space.
It is known to provide a dispensing auger running the length of a relatively long and narrow waste toner container. While such augers have been helpful in distributing waste toner along the length of the container, lateral distribution of the waste toner away from the auger has not been efficient. Further, toner can pack between the last flight of the auger and the back wall of the container, undesirably increasing the driving torque required for rotating the auger. Toner compressed between the last auger flight and back wall of the container also can leak around the auger shaft in the bearing hole in the back of the container. Toner particles leaking from the waste toner container can contaminate working surfaces of the machine, interfering with operation of the machine and degrading print quality.
What is needed is an augering system in a waste toner container which promotes lateral distribution of toner away from the auger, and which minimizes toner packing between the auger and container walls, thereby improving utilization of the container capacity; and reducing the possibility of toner leakage and the driving torque required for turning the auger.
The present invention provides a waste toner container for an imaging apparatus, the waste toner container having an auger therein designed to promote lateral distribution of toner as toner is moved from one end of the container to the other end of the container, while reducing toner spill from the container and reducing drive torque requirements.
The invention comprises, in one form thereof, a waste toner collecting device including a waste toner container having a bottom, a front wall, a back wall and side walls defining an enclosed space for receiving waste toner. An auger is operatively disposed in the container, the auger having a front end and a back end rotatably retained in the front wall and the back wall, respectively. The auger includes flights designed for decreasing toner transport in an axial direction and increasing toner transport in a lateral direction from the front end to the back end.
The invention comprises, in another form thereof, a method for distributing waste toner in a waste toner container, having steps of providing an elongated container having front and back walls spaced from each other a length of the container, and side walls spaced from each other a width of the container; providing an auger in the container, the auger extending along the container length and having adjacent flights along the length thereof, the auger having a front end and a back end; rotating the auger to transport toner along the flights; transporting the toner along the length at a decreasing rate from the front end to the back end; and transporting the toner across the width at an increasing rate from the front end to the back end.
The invention comprises, in yet another for m thereof; an auger for an elongated waste toner container having a length and a width, a front wall and a back wall spaced from each other defining the container length and side walls spaced from each other defining the container width. A shaft is rotatably disposed in the front wall and the back wall, and extends through the container length. Flights are provided on the shaft for transporting toner from the front wall toward the back wall. The flights are disposed at a varying pitch angle along the length to decrease toner transport in the direction of the length and increase toner transport in the direction of the width as the toner moves from the front wall to the back wall.
The invention comprises, in still another form thereof, an auger for an elongated waste toner container having a length and a width, a front wall and a back wall spaced from each other defining the container length and side walls spaced from each other defining the container width. A shaft is rotatably disposed in the front wall and the back wall and extending along the container length. Flights on the shaft are
disposed near the front wall and spaced from the rear wall to define a flightless segment of the shaft in the container.
An advantage of the present invention is that waste toner container volume is used more efficiently.
Another advantage is having a waste toner container auger having reduced drive torque requirements.
Yet another advantage is having a waste toner container having reduced toner spillage or leakage.